System for assisting rescuers in performing cardio-pulmonary resuscitation (CPR) on a patient

ABSTRACT

Systems and methods related to the field of cardiac resuscitation, and in particular to devices for assisting rescuers in performing cardio-pulmonary resuscitation (CPR) are described herein. In some aspects, the system includes a chest compression sensor providing movement information during a plurality of manual chest compressions performed by a rescuer on a chest of a patient; a release sensor providing information as to whether the rescuer&#39;s hands are in contact with the release sensor during manual chest compressions or not in contact with the release sensor between manual chest compressions; a computing unit; and an audio and/or visual display providing feedback received from the computing unit to the rescuer regarding chest compression rate, chest compression depth and whether the rescuer&#39;s hands are not in contact with the release sensor between manual chest compressions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/107,066, filed on Dec. 16, 2013, now U.S. Pat. No. 8,979,764, whichis a continuation of U.S. patent application Ser. No. 13/555,439 filedon Jul. 23, 2012, now U.S. Pat. No. 8,634,937, which claims benefit ofU.S. Provisional Application Serial No. 61/527,663 filed Aug. 26, 2011,the entire contents of each of which are hereby incorporated byreference.

TECHNICAL FIELD

This document relates to cardiac resuscitation, and in particular tosystems and techniques for assisting rescuers in performingcardio-pulmonary resuscitation (CPR).

BACKGROUND

The heart relies on an organized sequence of electrical impulses to beateffectively.

Deviations from this normal sequence is known as arrhythmia. Certainmedical devices include signal processing software that analyzeselectrocardiography (ECG) signals acquired from a medical patient (e.g.,a victim at a scene of an emergency) to determine when a cardiacarrhythmia such as ventricular fibrillation (VF) or shockableventricular tachycardia (VT) exists. These devices include automatedexternal defibrillators (AEDs), ECG rhythm classifiers, and ventriculararrhythmia detectors. An AED is a defibrillator—a device that deliverscontrolled electrical shock to a patient—while being relatively easy touse, such as by providing verbal prompts to a provider of care to “talk”the provider through a process of evaluating a patient for, attachingthe patient to, and activating, AED therapy. Certain of the medicaldevices just discussed are also capable of recognizing different cardiacwaveforms such normal sinus rhythm, aystole, VT and VF.

Many AEDs implement algorithms to recognize the VT and VF waveforms byperforming ECG analyses at specific times during a rescue event of apatient using defibrillation and cardio-pulmonary resuscitation (CPR).The first ECG analysis is usually initiated within a few seconds afterthe defibrillation electrodes are attached to the patient. Typically, ifthe ECG analysis detects a shockable rhythm, the rescuer is advised todeliver a defibrillation shock.

Following the defibrillator shock delivery or when any of the analysesdescribed above detects a non-shockable rhythm, treatment protocolsrecommended by the American Heart Association and European ResuscitationCouncil require performing CPR on the victim for a period of twominutes. The CPR includes rescue breathing and chest compressions.Following this period of CPR, the AED reinitiates ECG analysis asdescribed above. The sequence of one ECG analysis/defibrillation shockfollowed by 2 minutes of CPR continues in a repetitive fashion for aslong as the AED's power is turned on and the patient is connected to theAED device. Typically, the AED provides audio prompts to inform therescuer when analyses are about to begin, what the analysis resultswere, and when to start and stop the delivery of CPR.

Many studies have reported that the discontinuation of precordialcompression can significantly reduce the recovery rate of spontaneouscirculation and 24-hour survival rate for victims. Thus, it is useful torecognize abnormal heart rhythms during chest compressions. There isrecent clinical evidence showing that performing chest compressionsbefore defibrillating the patient under some circumstances can bebeneficial. Specifically, it is clinically beneficial to treat a patientwith chest compressions before defibrillation if the response times ofthe medical emergency system result in a delay of more than fourminutes, such that the patient is in cardiac arrest for more than fourminutes. Chest compression artifact rejection can employ spectralanalysis of the ECG, defibrillation success prediction, and therapeuticdecision-making typically specify a set of parameters in the ECGfrequency spectrum to be detected. For example, U.S. Pat. No. 5,683,424compares a centroid or a median frequency or a peak power frequency froma calculated frequency spectrum of the ECG to thresholds to determine ifa defibrillating shock is necessary.

SUMMARY

In some aspects, a method for providing adaptive CardiopulmonaryResuscitation (CPR) treatment to a person in need of emergencyassistance includes obtaining, by a computing unit, from anaccelerometer positioned to move in coordination with a patient'sbreastbone values for depths of a plurality of the chest compressions.The method also includes obtaining, by a computing unit, from a lightsensor affixed to the patient information about light detection. Themethod also includes determining, based on the information from thelight sensor, whether a rescuer is releasing the chest of a patientduring manual CPR chest compressions. The method also includes providingfeedback to a rescuer about chest compressions performed by the rescuerbased at least in part on the values for the depths of the plurality ofthe chest compressions and the determination of whether the rescuer isreleasing the chest of the patient.

Embodiments can include one or more of the following.

Determining whether the rescuer is releasing the chest of a patientduring manual CPR chest compressions can include determining a frequencyat which light is detected by the light sensor, comparing the determinedfrequency with a compression rate obtained from the accelerometer, anddetermining that the rescuer is not releasing the chest of a patient ifthe determined frequency at which light is detected by the light sensoris less than the compression rate obtained from the accelerometer.

Providing the feedback to the rescuer about chest compressions caninclude displaying on a graphical display screen of a defibrillator, anindication of the depths of one or more of the plurality of the chestcompressions, the rate of the chest compressions, and a releaseindicator.

Providing the feedback to the rescuer about chest compressions caninclude displaying a release indicator where the amount of fill in therelease indicator varies to indicate whether the rescuer is fullyreleasing between chest compressions.

Providing the feedback to a rescuer about chest compressions can includedisplaying an icon that indicates whether the chest compressions arebeing performed properly.

The method can also include receiving information about the patient'sheart activity and displaying on a graphical display, with the feedbackabout chest compressions, an electrocardiogram of the patient.

The computing unit can be integrated with a portable defibrillator.

The computing unit can be a touchscreen tablet computer.

In some aspects, an external defibrillator includes a light sensorarranged to contact a patient and obtain measurements regarding lightdetection, a computing unit connected to memory that stores computerinstructions for determining, based on the information from the lightsensor, whether a rescuer is releasing the chest of a patient duringmanual CPR chest compressions, and a video display screen for displayingfeedback to a rescuer about chest compressions performed by the rescuerbased at least in part on the determination of whether the rescuer isreleasing the chest of the patient.

Embodiments can include one or more of the following.

The computing unit can be configured to determine whether the rescuer isreleasing the chest of a patient during manual CPR chest compressions bydetermining a frequency at which a threshold amount of light is detectedby the light sensor, comparing the determined frequency with acompression rate obtained from an accelerometer, and determining thatthe rescuer is not releasing the chest of a patient if the determinedfrequency at which a threshold amount of light is detected by the lightsensor is less than the compression rate obtained from theaccelerometer.

The feedback to the rescuer about chest compressions can include arelease indicator.

An amount of fill in the release indicator can vary to indicate whetherthe rescuer is fully releasing between chest compressions.

The feedback to the rescuer about chest compressions can include an iconthat indicates whether the chest compressions are being performedproperly.

The external defibrillator can also include one or more sensorsconfigured to obtain information about the patient's heart activity.

The video display can be further configured to display anelectrocardiogram of the patient with the feedback about chestcompressions.

In some additional aspects, a method for providing adaptiveCardiopulmonary Resuscitation (CPR) treatment to a person in need ofemergency assistance includes obtaining, by a computing unit, from anaccelerometer positioned to move in coordination with a patient'sbreastbone values for depths of a plurality of the chest compressions,obtaining, by a computing unit, from a capacitive touch sensor affixedto the patient information about contact with the sensor, determining,based on the information from the capacitive touch sensor, whether arescuer is releasing the chest of a patient during manual CPR chestcompressions, and providing feedback to a rescuer about chestcompressions performed by the rescuer based at least in part on thevalues for the depths of the plurality of the chest compressions and thedetermination of whether the rescuer is releasing the chest of thepatient.

Embodiments can include one or more of the following.

Determining whether the rescuer is releasing the chest of a patientduring manual CPR chest compressions can include determining a frequencyat which contact with the capacitive touch sensor is detected based onthe information from the capacitive touch sensor, comparing thedetermined frequency with a compression rate obtained from theaccelerometer, and determining that the rescuer is not releasing thechest of a patient if the determined frequency at contact is detected bythe capacitive touch sensor is less than the compression rate obtainedfrom the accelerometer.

Providing the feedback to the rescuer about chest compressions caninclude displaying on a graphical display screen of a defibrillator, anindication of the depths of one or more of the plurality of the chestcompressions, the rate of the chest compressions, and a releaseindicator.

Providing the feedback to the rescuer about chest compressions caninclude displaying a release indicator where the amount of fill in therelease indicator varies to indicate whether the rescuer is fullyreleasing between chest compressions.

Providing the feedback to a rescuer about chest compressions can includedisplaying an icon that indicates whether the chest compressions arebeing performed properly.

The method can also include receiving information about the patient'sheart activity and displaying on a graphical display, with the feedbackabout chest compressions, an electrocardiogram of the patient.

In some additional aspects, an external defibrillator includes acapacitive touch sensor arranged to contact a patient and obtainmeasurements regarding contact with the capacitive touch sensor, acomputing unit connected to memory that stores computer instructions fordetermining, based on the information from the capacitive touch sensor,whether a rescuer is releasing the chest of a patient during manual CPRchest compressions, and a video display screen for displaying feedbackto a rescuer about chest compressions performed by the rescuer based atleast in part on the determination of whether the rescuer is releasingthe chest of the patient.

Embodiments can include one or more of the following.

The computing unit can be configured to determine whether the rescuer isreleasing the chest of a patient during manual CPR chest compressions bydetermining a frequency at which a capacitance indicative of contact ofa rescuer's hands with the capacitive touch sensor is detected by thecapacitive touch sensor, comparing the determined frequency with acompression rate obtained from an accelerometer, and determining thatthe rescuer is not releasing the chest of a patient if the determinedfrequency at which a threshold amount of light is detected by the lightsensor is less than the compression rate obtained from theaccelerometer.

The feedback to the rescuer about chest compressions can include arelease indicator with an amount of fill in the release indicatorvarying to indicate whether the rescuer is fully releasing between chestcompressions.

The feedback to the rescuer about chest compressions can include an iconthat indicates whether the chest compressions are being performedproperly.

The defibrillator can be further configured to receive information aboutthe patient's heart activity and displaying on a graphical display, withthe feedback about chest compressions, an electrocardiogram of thepatient.

Other features and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a diagram of one implementation including an automaticelectronic defibrillator (AED) and a multiple lead electrocardiograph(ECG) device.

FIG. 1B is a diagram of the AED of FIG. 1A.

FIG. 2 is a diagram of a defibrillation device with a display.

FIG. 3 is a flow chart showing actions taken to provide a releaseindicator.

FIGS. 4A and 4B are screenshots showing exemplary information presentedon a defibrillator display.

FIG. 5 is a diagram of defibrillation electrodes attached to a victim.

FIGS. 6A and 6B are diagrams of a victim receiving CPR.

FIGS. 7A and 7B are diagrams showing the placement of the hands relativeto a light sensor during the administration of CPR to a victim.

FIG. 8A shows an electrode package.

FIGS. 8B and 8C show defibrillation electrodes prior to removal from abacking.

FIGS. 9A and 9B are diagrams of a victim receiving CPR.

FIGS. 10A and 10B are diagrams showing the placement of the handsrelative to a capacitance sensor during the administration of CPR to avictim.

DETAILED DESCRIPTION

This description discusses systems and techniques for providing feedbackto a user/rescuer about the quality of CPR chest compressions. Ingeneral, a defibrillation device includes a light sensor attached to apatient or a CPR sensor and configured to provide feedback to a rescuerabout whether the rescuer is appropriately releasing the chest of thevictim during chest compressions.

Referring now to FIG. 1A, an AED 10 is shown that may be used to providea defibrillation shock at an appropriate time. In the figure, whichshows an example implementation, a rescuer uses an AED 10 toautomatically monitor a victim during cardiac resuscitation. The AED 10uses measured ECG signals to monitor the victim's heart, and charges thedefibrillation device within the AED while the victim is resuscitatedusing chest compressions techniques. In some examples, the manner inwhich the defibrillation device is charged (e.g., the rate of charge,the total amount of charge stored) can be based on the measured ECGsignals. Advantageously, charging the defibrillation device during CPRchest compressions reduces the amount of time that the victim is notreceiving chest compressions because, if a shockable rhythm exists, thedevice is armed and ready to deliver the shock as soon as the rescuercompletes the chest compressions.

As shown in FIG. 1B, the AED 10 includes a speaker 16, a display screen18, an analog-to-digital converter 20, a processor 22, and adefibrillator pulse generator 24. The analog-to-digital converter 20 isconnected to a set of ECG leads that are in turn attached to the victim.The ECG leads pass signals to the processor 22 for monitoring theelectrical rhythms of the victim's heart. The converter 20 sends thesignals from the ECG leads to the processor 22. The processor 22monitors the victim's heart for dangerous rhythms using the ECG signalswhile the victim is resuscitated using chest compressions techniques.

If the AED 10 detects a dangerous heart rhythm, the AED 10 generates analert signal. The alert signal is noticeable to the rescuer. The AED 10can generate a defibrillating shock to the victim when the rescuerissues a command to the AED 10 directing such a shock. Thedefibrillating shock is intended to remedy the dangerous rhythm of thevictim's heart.

The AED 10 also includes a charging module that may be configured tocharge the AED during chest compressions. The module can adaptivelycharge the AED based on monitored ECG signals and patient age. In someexamples, the defibrillator is pre-charged only if a shockable rhythm islikely to exist as determined by analysis of the monitored ECG signals.In some additional examples, the level of charge for the device isdetermined and set based on the monitored ECG signals. In someadditional examples, the method of charging (e.g., the rate of charge)varies based on the monitored ECG signals in an effort to conservepower. For example, if time allows, a capacitor may be charged moreslowly than it normally would in order to conserve power, but stillensure that the capacitor will reach its full charge just as thedefibrillator is needed by the rescuer.

The AED 10 uses a rhythm advisory method for, a) quantifying thefrequency-domain features of the ECG signals; b) differentiating normaland abnormal ECG rhythms, such as VF; c) detecting the onset of abnormalECG rhythms; and d) making decisions about the physiological states ofthe heart. This frequency-domain measure can be reliable with or withoutthe presence of the chest compression artifact in the ECG signals. TheAED 10, after identifying the current physiological state of the heart,can make a decision about appropriate therapeutic action for the rescuerto make and communicate the action to the rescuer using the speaker 16and the display screen 18.

The AED 10 may incorporate functionality for performing additionaltherapeutic actions such as chest compressions, ventilations, ordelivery of intravenous solution-containing metabolic or constitutivenutrients. Based on the results of the analysis of the rhythm advisorymethod, the AED 10 may automatically deliver the appropriate therapy tothe patient.

The AED 10 may also be configured in “advisory” mode wherein the AED 10will prompt the caregiver after the AED 10 has made a determination ofthe best therapy, and acknowledgement by the caregiver/device operator,in the form of a button press or voice-detected acknowledgement, isrequired before therapy is delivered to the patient.

The AED 10 analyzes the ECG signals to predict defibrillation success aswell as to decide whether it is appropriate to defibrillate or todeliver an alternative therapy such as chest compressions, drugs such asepinephrine, constitutive nutrients such as glucose, or other electricaltherapy such as pacing.

In some examples, one or more therapeutic delivery devices 30automatically deliver the appropriate therapy to the patient. Thetherapeutic delivery devices 30 can be, for example, a portable chestcompression device, a drug infusion device, a ventilator and/or a devicethat includes multiple therapies such as defibrillation, chestcompression, ventilation and drug infusion. The therapeutic deliverydevices 30 are physically separate from the defibrillator AED 10, andcontrol of the therapeutic delivery devices 30 may be accomplished by acommunications link 32. The communications link 32 may take the form ofa cable but preferably the link 32 is via a wireless protocol.

In other examples, control and coordination for the overallresuscitation event and the delivery of the various therapies may beaccomplished by a device 34 or processing element that is external tothe AED 10. For instance, the device 34 may download and process the ECGdata from the AED 10; analyze the ECG signals, perform relevantdeterminations like those discussed above and below based on theanalysis, and control the other therapeutic devices 30, including theAED 10. In other examples, the AED 10 may perform all the processing ofthe ECG, including analyzing the ECG signals, and may transmit to thecontrol device 34 only the final determination of the appropriatetherapy, whereupon the control device 34 would perform the controlactions on the other linked devices 30.

Chest compression artifacts can be separated from the ECG signalcomponents, making it possible for the AED 10 to process the ECG signalwithout halting the processing during chest compressions. Exemplarymethods for analyzing the ECG signal to determine if a shockable rhythmexists are described, for example, in U.S. Pat. No. 7,565,194, titled“ECG Rhythm Advisory Method,” the contents of which are herebyincorporated by reference in their entirety.

It has been recognized that good chest compressions during CPR isessential to saving more victims of cardiac arrest. The compression raterecommended by the American Heart Association in its guidelines is equalor greater than 100 compressions per minute. Many studies have reportedthat the discontinuation of chest compressions, such as is commonly donefor ECG analysis and charging of a defibrillator, can significantlyreduce the recovery rate of spontaneous circulation and 24-hour survivalrate. Because of safety issues with delivery of a high voltagedefibrillation shocks with voltages of 1000-2000 volts, rescuers aretaught to cease chest compressions and remove their hands from thevictim's chest before initiating the defibrillation shock. By analyzingECG signals during chest compressions as a mechanism to permit earliercharging of an energy delivery device (e.g., a capacitor) in adefibrillator device, the gaps in providing chest compressions can bereduced, and patient care increased.

FIG. 2 shows a defibrillation device 50 with a display portion 52 thatprovides information about patient status and CPR administration qualityduring the use of the defibrillator device. The data is collected anddisplayed in an efficient and effective manner to a rescuer. As shown ondisplay 52, during the administration of chest compressions, the device50 displays information about the chest compressions in box 54 on thesame display as a filtered ECG waveform 51 and a CO2 waveform 51(alternatively a SpO2 waveform can be displayed).

During chest compressions, the ECG waveform is generated by gatheringECG data point and accelerometer readings and filtering the motioninduced (e.g., CPR induced) noise from the ECG waveform. Measurement ofvelocity or acceleration of chest compression during chest compressionscan be performed according to the techniques taught by U.S. Pat. No.7,220,335, Method and Apparatus for Enhancement of Chest CompressionsDuring Chest Compressions, the contents of which are hereby incorporatedby reference in their entirety. Displaying the filtered ECG waveformhelps clinicians reduce interruptions in CPR because the displayedwaveform is easier for the rescuer to decipher. If the ECG waveform isnot filtered, artifacts from manual chest compressions make it difficultto discern the presence of an organized heart rhythm unless compressionsare halted. Filtering out this artifact allows clinicians to view theunderlying rhythm without stopping chest compressions.

As shown in display 50, the filtered ECG waveform 51 is a full lengthwaveform filling the entire span of the display device while the secondwaveform (e.g., the CO2 waveform 52) is a partial length waveform andfills only a portion of the display. A portion of the display beside thesecond waveform provides the CPR information in box 54. For example, thedisplay splits the horizontal area for the second waveform in half,displaying waveform 52 on left and CPR information on the right in box54.

The CPR information in box 54 is automatically displayed whencompressions are detected. The information about the chest compressionsdisplayed in box 54 includes rate 58 (e.g., number of compressions perminute) and depth 56 (e.g., depth of compressions in inches ormillimeters). The rate and depth of compressions can be determined byanalyzing accelerometer readings. Displaying the actual rate and depthdata (in addition to or instead of an indication of whether the valuesare within or outside of an acceptable range) is believed to provideuseful feedback to the rescuer. For example, if an acceptable range forchest compression depth is between 1.5-2 inches, providing the rescuerwith an indication that his/her compressions are only 0.5 inches canallow the rescuer to determine how to correctly modify his/heradministration of the chest compressions.

The information about the chest compressions displayed in box 514 alsoincludes a perfusion performance indicator (PPI) 60. The PPI 60 is ashape (e.g., a diamond) with the amount of fill in the shape differingto provide feedback about both the rate and depth of the compressions.When CPR is being performed adequately, for example, at a rate of about100 compressions/minute (CPM), with the depth of each compressiongreater than 1.5 inches, the entire indicator will be filled. As therate and/or depth decreases below acceptable limits, the amount of filllessens. The PPI 60 provides a visual indication of the quality of theCPR such that the rescuer can aim to keep the PPI 60 completely filled.While some exemplary types of information displayed to the rescuer havebeen described herein, additional information about CPR quality andphysiological parameters of the victim can be displayed in conjunctionwith or instead of the information described herein. For example, arelease indication can be displayed with other information about the CPRquality of measured physiological parameters. Exemplary displays andmeasurements are described, for example, in U.S. patent application Ser.No. 13/025,348 filed on Feb. 11, 2011, now U.S. Pat. No. 8,880,166, andentitled “DEFIBRILLATOR DISPLAY” and in pending U.S. patent applicationNo. 13/081,217 filed on Apr. 6, 2011, which published as U.S. PatentApplication Pub. No. 2011/0284004, and which is entitled “WIRELESSVENTILATOR REPORTING,” the contents of each of which are herebyincorporated by reference.

In addition to measuring information about the rate and depth of CPRchest compressions, in some examples the defibrillator device providesinformation about whether the rescuer is fully releasing his/her handsat the end of a chest compression. For example, as a rescuer tires, therescuer may begin leaning on the victim between chest compressions suchthat the chest cavity is not able to fully expand at the end of acompression. If the rescuer does not fully release between chestcompressions the quality of the CPR can diminish. As such, providing avisual or audio indication to the user when the user does not fullyrelease can be beneficial.

FIG. 3 is a flow chart showing actions taken to provide an indication ofwhether a rescuer is fully releasing between chest compressions. At box62, the defibrillator device measures depth, rate, and release of CPRchest compressions. The depth, rate, and release of CPR chestcompressions can be determined based on information collected from anaccelerometer, light sensor, capacitive touch sensor, or other devices.Based on the collected information, at box 64, the defibrillatordetermines whether the rescuer is fully releasing between chestcompressions. At box 66, the defibrillator provides an indicator on adisplay that includes information about whether the rescuer is fullyreleasing. For example, the display on the defibrillator can include arelease indication box where the amount of fill in the box varies toindicate whether the rescuer is fully releasing between chestcompressions. For example, as shown in FIG. 4A, when the rescuer isfully releasing the box 70 can be fully filled. When the rescuer is notfully releasing the amount of fill in the release indication box isdecreased such that the box is only partially filled (e.g., as shown inbox 72 of FIG. 4B).

In some examples, the depth and rate of CPR chest compressions can bedetermined based on information collected from an accelerometer whilethe release of the CPR chest compressions can be based on informationcollected from a light or capacitive touch sensor. For example, as shownin FIG. 5, a CPR monitoring device 86 that includes a light sensor orcapacitive touch sensor 88 and an accelerometer can be affixed to avictim's chest at a location corresponding to the location of therescuer's hands when delivering manual chest compressions prior to theadministration of CPR. The light sensor measures light impinging on thesensor and provides the information to a computing device in thedefibrillator. The defibrillator processes the information to determinewhether the rescuer's hands are in contact with the light sensor 88.More particularly, because the device 86 is affixed to the victim'schest or on top of the CPR sensor at a location corresponding to thelocation of the rescuer's hands when delivering manual chestcompressions, the presence or absence of light detection by the lightsensor 88 can be used to determine whether the rescuer is fullyreleasing the chest of the victim during the administration of chestcompressions.

The light sensor 88 can be any device that is used to detect light.Exemplary light sensors include photocells or photoresistors that changeresistance when light shines on it, charged coupled devices (CCD) thattransport electrically charged signals, photomultipliers that detectlight and multiply it, and the like. Capacitive sensing is a technologybased on capacitive coupling between conductive or has a dielectricdifferent than that of air and the sensor. When the human handsapproaches or touches the capacitive sensor, this detects this movementor touch of the hand and measure a change in capacitance. The level ofcapacitance can be used by the processor or device to determine whetherthe rescuer hand is touching the capacitor sensor pad.

FIGS. 6A-B and 7A-B show exemplary light sensor during CPR compressions.As shown in FIGS. 6A and 7A, when the rescuer's hands 92 are raised awayfrom the victim's chest and are not in contact with the victim's chest90 (e.g., when the rescuer releases from a compression), the lightsensor 88 is uncovered. Thus, when the rescuer's hands are raised awayfrom the victim's chest light 96 can reach the light sensor 88 and thelight sensor detects the presence of the light 96. In contrast, as shownin FIGS. 6B and 7B, when the rescuer's hands 92 are in contact with thevictim's chest 90 (e.g., when the rescuer is providing a compression)the light sensor 88 is covered. When the light sensor is covered, lightis not able to reach the light sensor 88. Thus, the presence and absenceof light measured by the light sensor can be used to determine whetherthe rescuer is fully releasing his/her hands from the victim's chest 90;when light is detected the rescuer has released and when light is notdetected the rescuer is maintaining physical contact with the victim.

In some examples, the information from the light sensor can be comparedto CPR compression rate information from the accelerometer to determinewhether the user is releasing the victim's chest fully. Moreparticularly, if the rescuer is releasing the victim's chest fully,light should be observed by the light sensor for every compression.Thus, the defibrillation device can determine a frequency at which athreshold amount of light is detected by the light sensor and comparethe determined frequency with a compression rate obtained from theaccelerometer. If the determined frequency from the light sensor is thesame (or within an acceptable range from) the compression rate obtainedfrom the accelerometer, the defibrillation device can determine that therescuer is appropriately releasing the victim's chest. On the otherhand, if the frequency from the light sensor is less than thecompression rate, the defibrillation device can determine that therescuer is not appropriately releasing the victim's chest.

While in the example described above, the presence/absence of light wasused to determine the release of the rescuer's hands from the victim'schest, in some additional examples a change in light measured by thelight sensor 88 can be used to determine the presence/absence of therescuer's hands. For example, the rescuer may not fully cover the lightsensor 88 when providing compressions. However, if a portion of thelight sensor 88 is covered, a change in the intensity or amount of lightmeasured by the light sensor will be observed when the rescuer liftshis/her hands. This change in intensity can be used to determinepresence/absence of the rescuer's hands.

In some additional examples, the light sensor 88 can be used to detectthe removal of the electrodes from a package and can be used to begininstructions to a rescuer about how to apply the electrodes to thevictim.

FIG. 8A shows an assembled electrode package 110 with multiconductorelectrical lead 120 and label 112. The package is opened by grasping theloose flaps 116 at arrow label 118, and peeling back the top flap. Asthe flaps are pulled apart, releaseable peripheral adhesive 114 parts.When a light sensor is included in the assembled electrode package 110,light is unable to impinge on the light sensor 161. As such, informationfrom the sensor can be used to determine that the rescuer has not yetopened the electrode package regardless of whether the leads 120 havebeen plugged into a defibrillation device. As such, if thedefibrillation device detects that the leads 120 have been inserted intothe defibrillation device but the light sensor 161 does not indicate thepresence of light, the defibrillation device can provide instructions tothe rescuer about how to open the electrode package 110.

FIGS. 8B and 8C show views of the electrodes 150 a and 150 b, anaccelerometer 160, a light sensor 161, and styrene sheet 140 afterremoval from the electrode package 110. Before the package is opened,the styrene sheet 140 is folded along fold line 151 in the form of aclosed book (e.g., as shown in FIG. 8B), with the electrodes 50 a and 50b and accelerometer 60 peelably attached to the interior facing surfacesof the book. The accelerometer works with electronics in thedefibrillator to determine the depth of compressions during CPR. Thelight sensor 161 works with electronics in the defibrillator todetermine whether the rescuer is appropriately releasing the victim'schest between compressions (e.g., as described herein). ECG electrodes(not shown) are built into one of electrode 150 a or 150 b (each islocated at approximately the corners of the triangular shape of theelectrode). Until the book is unfolded, the light sensor 161 is coveredby the opposite side of the styrene sheet 140 and light is unable toimpinge on the light sensor. On opening the package, the book isunfolded, so that the electrodes and accelerometer are presented to theuser as shown in FIG. 8C. Upon unfolding the book, the light sensor 161is uncovered and light is able to reach the light sensor. Thus, theunfolding of the book (and the resulting light measurement from thesensor 161) indicates to the defibrillation device that the user hasopened the package 110 and is ready to receive information (e.g., audioor visual instructions) about the application of the electrodes to thevictim.

FIGS. 9A-B and 10A-B show capacitance sensor during CPR compressions. Asshown in FIGS. 9A and 10A, when the rescuer's hands 92 are raised awayfrom the victim's chest and are not in contact with the victim's chest90 (e.g., when the rescuer releases from a compression), the capacitancesensor 87 is uncovered. Thus, when the rescuer's hands are raised awayfrom the victim's chest capacitance measured by the capacitance sensor87 is based on the dielectric of air. In contrast, as shown in FIGS. 9Band 10B, when the rescuer's hands 92 are in contact with the victim'schest 90 (e.g., when the rescuer is providing a compression) thecapacitance sensor 87 is covered and contact is made between therescuer's hands and the sensor 87. When the human hands approach ortouch the capacitive sensor 87, the sensor 87 detects this movement ortouch of the hand and measures a change in capacitance. Thus, themeasured capacitance level can be used by the processor or device todetermine whether the rescuer hand is touching the capacitor sensor 87and can be used to determine whether the rescuer is fully releasinghis/her hands from the victim's chest 90; when capacitance remains at alevel indicating that the rescuer's hands are in contact with thecapacitance sensor 87, the rescuer is not fully releasing his/her handsbetween compressions.

In some examples, the information from the capacitance sensor can becompared to CPR compression rate information from the accelerometer todetermine whether the user is releasing the victim's chest fully. Moreparticularly, if the rescuer is releasing the victim's chest fully, achange in capacitance should be observed by the capacitance sensor forevery compression. Thus, the defibrillation device can determine afrequency at which a threshold change in capacitance is detected by thecapacitance sensor and compare the determined frequency with acompression rate obtained from the accelerometer. If the determinedfrequency from the capacitance sensor is the same (or within anacceptable range from) the compression rate obtained from theaccelerometer, the defibrillation device can determine that the rescueris appropriately releasing the victim's chest. On the other hand, if thefrequency from the capacitance sensor is less than the compression rate,the defibrillation device can determine that the rescuer is notappropriately releasing the victim's chest.

While at least some of the embodiments described above describetechniques and displays used in conjunction with an AED device, similartechniques and displays can be used with other defibrillator devices.Exemplary professional grade defibrillator devices include the R series,E series, Propaq MD, or M series devices manufactured by ZOLL Medical,MA and the Philips MRX or Philips XL devices.

Additionally, the defibrillator may take the form of a wearabledefibrillator such as the LifeVest, manufactured by ZOLL Medical(Chelmsford, Mass.).

Many other implementations other than those described may be employed,and may be encompassed by the following claims.

What is claimed is:
 1. A system for assisting a rescuer in performingcardio-pulmonary resuscitation (CPR) on a patient, the systemcomprising: a proximity sensor configured to sense a level of intensityindicative of whether a rescuer's hand is in relative proximity with theproximity sensor, wherein the proximity sensor is configured to bepositioned in proximity with a patient's chest at a locationcorresponding to a location of the rescuer's hand when deliveringcompressions to the patient's chest; a chest compression sensorconfigured to sense movement of the patient's chest upon compressionperformed by the rescuer; a computing unit configured to determinewhether the rescuer is releasing the chest in between chest compressionsbased upon the sensed level of intensity, and determine chestcompression rate and chest compression depth based upon movementinformation received from the chest compression sensor; and a feedbackdevice configured to provide feedback received from the computing unitto the rescuer regarding chest release, the feedback comprising anindicator of the chest compression rate and the chest compression depth.2. The system according to claim 1, wherein the computing unitdetermines whether the rescuer is fully releasing the chest in betweenchest compressions based on the level of intensity sensed by theproximity sensor.
 3. The system according to claim 2, wherein thefeedback device is configured to provide feedback received from thecomputing unit to the rescuer regarding whether the rescuer is fullyreleasing the chest in between chest compressions.
 4. The systemaccording to claim 1, wherein the feedback device is configured toprovide feedback received from the computing unit to the rescuerregarding whether the rescuer's hand is in contact or not in contactwith the proximity sensor during chest compressions.
 5. The systemaccording to claim 1, wherein the chest compression sensor comprises atleast one accelerometer.
 6. The system according to claim 1, wherein theindicator is a performance indicator.
 7. The system according to claim1, wherein the indicator comprises a shape which is filled by a fillamount with the fill amount in the shape differing to provide feedbackabout both the rate and depth of the compressions.
 8. The systemaccording to claim 7, wherein the indicator provides a visual indicationof quality of CPR, such that the rescuer can attempt to keep the shapecompletely filled during compressions.
 9. The system according to claim7, wherein the shape is entirely filled when the compression rate isgreater than 100 compressions/minute and the compression depth isbetween about 1.5 and 2.0 inches.
 10. The system according to claim 1,wherein the feedback device comprises a visual display comprising arelease indication.
 11. A system for assisting a rescuer in performingcardio-pulmonary resuscitation (CPR) on a patient, the systemcomprising: a proximity sensor configured to sense a level of intensityindicative of whether a rescuer's hand is in relative proximity with theproximity sensor, wherein the proximity sensor is configured to bepositioned in proximity with a patient's chest at a locationcorresponding to a location of the rescuer's hand when deliveringcompressions to the patient's chest; a computing unit configured todetermine whether the rescuer is releasing the chest in between chestcompressions based upon the sensed level of intensity; and a feedbackdevice configured to provide feedback received from the computing unitto the rescuer regarding chest release, the feedback device comprising avisual display comprising a release indication, wherein the releaseindication comprises a shape which is filled by a fill amount when therescuer's hand is not in contact with the proximity sensor, and whereinthe fill amount is reduced when the rescuer's hand is in contact withthe proximity sensor.
 12. The system according to claim 1, wherein theproximity sensor comprises a light sensor configured to obtainmeasurements regarding light detection.
 13. The system according toclaim 1, wherein the proximity sensor comprises a capacitive touchsensor configured to obtain measurements regarding contact with thecapacitance touch sensor.
 14. The system according to claim 1, furthercomprising one or more sensors configured to obtain information aboutheart activity of the patient.
 15. The system according to claim 1,wherein the feedback device comprises one or more of a visual displayand an audio device.
 16. An external defibrillator comprising: adefibrillation pulse generator for generating a shock to a patient; aproximity sensor configured to sense a level of signal intensityindicative of whether a rescuer's hand is in relative proximity with theproximity sensor, wherein the proximity sensor is configured to bepositioned in proximity with a patient's chest at a locationcorresponding to a location of the rescuer's hand when deliveringcompressions to the patient's chest; a chest compression sensorconfigured to sense movement of the patient's chest; a computing unitconfigured to process the sensed level of intensity from the proximitysensor, and process movement information received from the chestcompression sensor; and a feedback device for providing feedbackreceived from the computing unit to the rescuer regarding whether therescuer's hand full releases the patient's chest between chestcompressions, the feedback being based, at least in part, on the sensedlevel of intensity and the movement information.
 17. The defibrillatoraccording to claim 16, wherein the defibrillation pulse generator isconfigured to provide a shock to the patient at a time when the rescueris releasing the patient's chest.
 18. A method for providingCardiopulmonary Resuscitation (CPR) treatment to a patient, the methodcomprising: obtaining, from a proximity sensor, a level of intensityindicative of whether a rescuer's hand is in relative proximity to theproximity sensor, wherein the proximity sensor is configured to bepositioned in proximity to a patient's chest at a location correspondingto a location of the rescuer's hand when delivering compressions to thepatient's chest; obtaining, from a chest compression sensor, informationabout chest compressions performed by the rescuer on the patient'schest; determining, by a computing unit, whether the rescuer isreleasing the chest in between chest compressions based on the sensedlevel of intensity; determining, by the computing unit, a chestcompression rate and a chest compression depth based on movement sensedby the chest compression sensor; and providing feedback received fromthe computing unit to the rescuer regarding chest release, the feedbackcomprising an indicator representative of the chest compression rate andthe chest compression depth.
 19. The method according to claim 18,wherein the chest compression sensor comprises at least oneaccelerometer.
 20. The system of claim 1, wherein the feedback furthercomprises an indication representative of actual compression rate and/oractual compression depth.
 21. The system of claim 20, wherein theindication representative of actual compression rate and/or actualcompression depth comprises a numerical value for chest compression rateand/or chest compression depth.
 22. The system of claim 1, wherein thecomputing unit is configured to determine whether the rescuer's handfully releases the patient's chest between chest compressions based, atleast in part, on the sensed level of intensity and the determined chestcompression rate and/or chest compression depth.
 23. The system of claim22, wherein determining whether the rescuer's hand fully releases thepatient's chest comprises comparing a frequency of release determinedbased on the sensed level of intensity and the determined chestcompression rate.
 24. The system of claim 23, wherein the feedbackfurther comprises a release indication, the release indicationcomprising a shape which is filled by a fill amount when the rescuer'shand fully releases the patient's chest between chest compressions, andwherein the fill amount is reduced when the rescuer's hand does notfully release the patient's chest between chest compressions.
 25. Asystem for assisting a rescuer in performing cardio-pulmonaryresuscitation (CPR) on a patient, the system comprising: a proximitysensor configured to sense a level of intensity indicative of whether arescuer's hand is in relative proximity with the proximity sensor,wherein the proximity sensor is configured to be positioned in proximitywith a patient's chest at a location corresponding to a location of therescuer's hand when delivering compressions to the patient's chest; achest compression sensor configured to sense movement of the patient'schest; a computing unit configured to determine whether the rescuer'shand fully releases the patient's chest between chest compressions, thedetermination being based, at least in part, upon the level of intensitysensed by the proximity sensor and movement information sensed by thechest compression sensor; and a feedback device configured to providefeedback received from the computing unit to the rescuer regarding fullrelease of the patient's chest.
 26. The system of claim 25, whereindetermining whether the rescuer's hand fully releases the chest betweenchest compressions comprises comparing a frequency of chest releasedetermined based upon the sensed level of intensity and a chestcompression rate determined based upon the movement information.
 27. Thesystem of claim 25, wherein the computing unit is configured todetermine that the rescuer's hand fully releases the patient's chestwhen the frequency of chest release is within a predetermined percentageof the determined chest compression rate.
 28. The system of claim 25,wherein the computing unit is configured to determine that the rescuer'shand does not fully release the patient's chest when the chestcompression rate is greater than the frequency of chest release.
 29. Thesystem of claim 25, wherein the feedback device comprises a visualdisplay, the visual display comprising a shape which is filled by a fillamount when the rescuer's hand fully releases the patient's chestbetween chest compressions, and wherein the fill amount is reduced whenthe rescuer's hand is not fully releasing the patient's chest betweenchest compressions.